High severity · published Feb 3, 2026
CVE-2026-25223
Fastify's Content-Type header tab character allows body validation bypass
7.5
CVSS
0.9%
EPSS
No
On KEV
Description
Fastify is a fast and low overhead web framework, for Node.js. Prior to version 5.7.2, a validation bypass vulnerability exists in Fastify where request body validation schemas specified by Content-Type can be completely circumvented. By appending a tab character (\t) followed by arbitrary content to the Content-Type header, attackers can bypass body validation while the server still processes the body as the original content type. This issue has been patched in version 5.7.2.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.9% · higher than 59% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FA
fastify · fastify
< 5.7.2 · source: vendor, NVD
RH
Red Hat Enterprise Linux AI (RHEL AI) 3 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat OpenShift AI (RHOAI) · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat OpenShift AI 2.16 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat OpenShift AI 2.25 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat OpenShift Dev Spaces 3.27 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-25223
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-25223
Product
https://fastify.dev/docs/latest/Reference/Validation-and-Serialization
Product
https://github.com/fastify/fastify/blob/759e9787b5669abf953068e42a17bffba7521348/lib/content-type-parser.js#L125
Product
https://github.com/fastify/fastify/blob/759e9787b5669abf953068e42a17bffba7521348/lib/validation.js#L272
Patch
https://github.com/fastify/fastify/commit/32d7b6add39ddf082d92579a58bea7018c5ac821
Mitigation
https://github.com/fastify/fastify/security/advisories/GHSA-jx2c-rxcm-jvmq
Permissions Required
https://hackerone.com/reports/3464114
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